If you see injustice or unfairness, you're supposed to speak out, right? What happens when the injustice you see relates to the estate of a friend or loved one, and you believe that the will that has been filed isn't actually valid. Perhaps the information in the will just seems bizarre and isn't in line at all with what you knew about the person's wishes. Maybe you even know about another possible will and thing that one is the valid one. What do you do about these concerns?
On the surface, the answer seems easy: You contest the will. In reality, not everyone is going to have the same luck contesting a will. In fact, bringing a contest simply because you think things seem "fishy" isn't likely to get you very far in the courts.
Two sets of people are likely to have the most luck with will contests: those that would have legally been heirs but aren't in the will and those that were in previous versions of a will. If the law says you are an heir and you aren't included in the will, then you have some strong legal premises to stand on in declaring a will invalid. For example, if the spouse or children of someone are written out of a will, they might be able to stake a claim on the estate via probate litigation.
If you were previously made an heir in a will and the person changed the his or her will, then you also have an argument to make. The chance of successfully contesting the will is even greater if you can show evidence of foul play or undue influence with regard to the new version of the will.
This doesn't mean that you can't contest a will if you don't fit one of the above categories. You should talk to a legal professional before taking action, though, because the burden of proof regarding the invalidity of the will and why it matters is on you.
Source: The Balance, "Who Can Contest a Will? Having Enough Legal Standing," Julie Garber, accessed Feb. 03, 2017